April - June 2007 - Kasetsart University

without coating and coated with pectins were not
significantly different (p>0.05). Their values were
between 71.67-73.00, 13.07-14.32 and 78.97-
80.92 for L*, a* and b* values, respectively. The
rice premix has yellow color (high b* value) due
to addition of riboflavin.
1.2 Chemical properties
Moisture contents of all rice premix
samples were not significantly different (p>0.05).
Kasetsart J. (Nat. Sci.) 41(2) 359
Their values were between 8.01-8.93%. Table 1-3
showed the loss of thiamine riboflavin and niacin
in washed and cooked rice premix without coating
and coated with pectins in excess water and
draining. The rice premix coated with pectins
showed lower vitamin losses after washing than
those without coating. The higher degree of
methoxyl pectin showed the lower vitamin losses
in washed rice premix than lower degree of
Table 1 Thiamine contents in rice premix, washed and cooked rice in excess water and draining,
washing and cooking losses.
Rice premix Thiamine contents (mg/100 g) Washing loss Cooking
Rice premix Washed rice Cooked rice (%) loss (%)
premix premix (ns)
- No pectin coating
- Coated with pectin
23.47 ± 0.13 4.92 ± 0.24 1.68 ± 0.20 79.03 ± 1.14 a 92.84 ± 0.88
36 % degree of methoxyl
- Coated with pectin
31 % degree of methoxyl
25.84 ± 0.12 11.41 ± 0.02 1.37 ± 0.32 55.86 ± 0.29 c 94.69 ± 1.28
with 18 % degree of amidation
- Coated with pectin
28 % degree of methoxyl
19.28 ± 4.50 8.19 ± 0.93 1.46 ± 0.05 56.90 ± 5.23 c 92.15 ± 2.09
with 21% degree of amidation 24.25 ± 0.27 7.57 ± 0.15 0.84 ± 0.00 68.78 ± 0.99 b 96.67 ± 0.23
Note: alphabets a-c were different within column mean values were significantly different (p≤0.05)
ns means values within column were not significantly different (p>0.05)
Table 2 Riboflavin contents in rice premix, washed and cooked rice in excess water and draining,
washing and cooking losses.
Rice premix Riboflavin contents (mg/100 g) Washing loss Cooking
Rice premix Washed rice Cooked rice (%) loss (%)
premix premix (ns)
- No pectin coating
- Coated with pectin
41.98 ± 2.76 8.19 ± 1.41 2.82 ± 0.20 80.54 ± 2.07 a 93.28 ± 0.50
36 % degree of methoxyl
- Coated with pectin
31 % degree of methoxyl
38.68 ± 3.46 12.52 ± 1.46 3.01 ± 0.25 67.66 ± 0.90 c 92.17 ± 1.34
with 18 % degree of amidation
- Coated with pectin
28 %degree of methoxyl
45.48 ± 0.30 12.34 ± 0.33 3.32 ± 0.01 72.86 ± 0.55 b 92.69 ± 0.08
with 21 % degree of amidation 38.81 ± 1.79 10.91 ± 0.50 2.90 ± 0.02 71.28 ± 2.60 bc 92.53 ± 0.29
Note: alphabets a-c were different within column mean values were significantly different (p≤0.05)
ns means values within column were not significantly different (p>0.05)